1. Field of the Invention (Technical Field)
The present invention relates to systems and apparatuses for detecting passage of vehicles and directions of travel thereof.
2. Background Art
A major cause of high speed collisions and concomitant traffic fatalities and serious injuries is the passage of traffic in the wrong direction in a one-way lane. Especially for lanes having a history of accidents due to wrong-way traffic, it is desirable to deploy a robust and substantially error-free system of dynamically warning of wrong-way traffic. Both the wrong-way vehicle and vehicles proceeding correctly must be warned. The present invention provides such a system.
Related attempts at accurate traffic detection have suffered various flaws. U.S. Pat. No. 3,641,569, to Bushnell et al., entitled "Highway Vehicle Sensor System", discloses a device for detecting direction of travel requiring sets of three loops, each set with a main loop and two probe loops. U.S. Pat. No. 3,863,206, to Rabie, entitled "Digital Vehicle Detector", discloses the use of overlapping pairs of loops and sequentially cyclically energizing different-frequency oscillators, but does not appear to provide for detection of direction of travel. U.S. Pat. No. 4,320,380, to Berard et al., entitled "Electronically Controlled Safety Mechanism for Highway Exit Ramp", discloses wrong-way detection and warning using loop detectors, but does not provide for overlap of such loops.
Patents related to the subject matter of this invention but not believed particularly significant include U.S. Pat. No. 3,697,996, to Elder et al., entitled "Electromagnetic Field Producing Apparatus and Method for Sequentially Producing a Plurality of Fields"; U.S. Pat. No. 3,588,805, to Davin, entitled "Highway Intersection Warning System"; U.S. Pat. No. 3,587,012, to Pickarsky, entitled "Magnetically Actuated Detecting and Switching Device"; U.S. Pat. No. 3,536,900, to Iwamoto et al., entitled "Apparatus for Detecting Traffic Delay"; U.S. Pat. No. 3,090,042, to Kleist et al., entitled "Interrogator-Responder Signalling System"; U.S. Pat. No. 2,537,298, to Baughman, entitled "Traffic Controlling Apparatus"; U.S. Pat. No. 2,532,231, to Jarvis, entitled "Traffic Detector"; and U.S. Pat. No. 1,610,692, to Logwood, entitled "Railroad Signaling System".